Plates adapted for use in electrolytic devices



Sept 22, 1953 J. B. BRENNAN A 2,653,119

PLATES ADAPTED FOR USE IN ELECTROLYTIC DEVICES Filed Sep. 13, 1951 INVENTOR Rf" 03E/H e BRENNAN BYM,M%W

ATTORNEYS Patented Sept. 22, 1953 UNITED vSTATES PATENT OFFICE PLATES ADAPTED FOR USE IN ELECTROLYTIC DEVICES 9 Claims.

This application is a continuation-in-part of my co-pending application Serial No. 25,785 filed May 7, 1948, now abandoned.

This invention relates to plates adapted for use in electrolytic devices su-h as, for example, electrolytic condensers.

Such plates are described in my U. S, Patent No.` 2,104,018, issued January 4, 1938.

Electrolytic condensers of this type include electrodes comprising a layer of porous aluminum or other film forming metal. As commercially made, these electrodes have been fabricated by spray depositing molten film forming metal into and on one or more layers of woven gauze.

An object of my present invention is to produce an electrode having a base of material which can be manufactured much more inexpensively than gauze, and which is characterized by the fact that it has high tensile strength when wet.

In order to facilitate an understanding of the invention, reference is made to the accompanying drawings in which:

Figure 1 is a perspective view of an electrolytic condenser (partially unrolled) embodying an electrode constructed according to the present invention;

Figure 2 is a fragmentary magnified cross sectional view of a portion of an electrode according to the present invention;

Figure 3 is another fragmentary magnified cross sectional view of a portion of an electrode according to the present invention showing a modified form of construction;

Figure 4 is a further fragmentary magnified cross sectional view of a portion of an electrode according to the present invention showing another modified form of construction.

The material which I propose as a base for depositing spray deposited molten film forming metal is, according to my invention, a carded fabric comprising textile fibers, either natural and/or synthetic, in which the preponderance of the fibers extend lengthwise of the fabric in such a. Way that they are preferably bound together by thermoplastic and/or thermosetting particles or fibers at spaced intervals throughout.

The method of making the base material on which the film forming spray deposited metal is deposited according to my invention is to first make a layer of suitable fibers, such as of cotton and thermosetting synthetic fibers, which layer is in the form of-a thin batt and thereafter subjecting this batt to calendering, as between heated rolls to at least partially coalesce the thermoplastic or thermosetting fibers so that a smooth porous soft inexpensive material is produced in the form of a continuous band, preferably not over .004" in thickness.

The above described batt prior to calendering may have thermoplastic or thermosetting particles distributed at spaced intervals therein as in addition to synthetic iibers, for example, by spraying cellulose acetate particles or urea formaldehyde resin particles therein prior to calendering and heat treatment thereof, Other suitable thermoplastic or thermosetting materials may be used. For example, nylon or cellulose acetate vfibers and cotton fibers and urea formaldehyde particles may be incorporated in a batt and calendered under heat and pressure.

It is essential to use fibers and other thermoplastic materials which are non-contaminating in subsequent use in an electrolytic condenser when subjected to electrolysis.

It is essential that fibers and bonding agents used do not give ofi any chloride or sulphate ions and that they are free from metals and any other impurities which. might react deleteriously in use with film forming electrolytes and film forming electrodes.

It is essential, according to my invention, that the bonded calendered batt have sufficient tensile strength to permit its being passed continuously in front of devices for spray depositing molten film forming metal Without breaking up or igniting due to the temperatures or mechanical stress encountered and it must be closely formed enough so that the spray deposited metal does not pass through it in suiicient quantities to form a layer on the backing member over which it passes while it is being spray deposited. This backing member preferably comprises a fluidcooled metallic surface, one of Whose purposes is to conduct heat away from the above described base onto which a continuous layer of coherent conductive porous lm forming particles is spray deposited, The calendered batts may be spray deposited in multiple layers, but if this is done, the spray deposited electrode should preferably not exceed .010 thickness.

According to my invention it is preferable that the preponderance of fibers be of a type which after heat calendering and/or heat treatment will retain their individual shape and it is desirable to use a small portion of bonding particles, or fibers such as on the order of from 1% to 40% by weight of coalescing bers or particles.

The continuous tape which, according to my invention, is used as a base for spray depositing iilm forming electrodes thereon also is characterized by the fact that after calendering it is soft and porous and the molten metal when spray deposited thereon is preferably projected at such velocity that it penetrates into the fibers of the calendered batt so that the molten metal particles lend additional strength, especially wet strength, to a resultant electrode material. This is due to the fact that the` molten metal particles interlock with the textile fibers.

It is essential that electrodes made according to my invention be continuous and they are generally made at least several -hundred feet in length without interruption and it `is essential that they have a Wet strength beyond the wet strength of ordinary unwoven porous wet laid fibrous layer base electrodes in order to admit of their being passed continuously'through hot electrolyte for formation of dielectric 'iil'ins thereon and for withstanding the tensions Vusually encountered in helically winding these electrodes with spacers into electrolyticfcondensers. The electrolyte in which these electrode tapesare lm formed are usuallyy kept near the boiling point of Water and it is"helpful in avoiding interruptions in the 'process'that the electrode tape material have lgood tensile strength as well as high Vporosity to avoid breaking and so that commercial 'formation apparatus can be used in conjunction with the article of my invention and sothat 'conventional winding apparatus and impregnation apparatus can be used therewith.

Calendered batts substantially free of chlorides and sulphatesand 4having a preponderancel of lngitiidiii'al` textile 'fibers rnade according 'to my invention can also 'be used advantageously as separators 'in electrolytic condensers and have excellent electrolyte permeability and electrolyte retention characteristics AAs shown in Figure 1, the condenser comprises apair of electrodes I and 2 having terminals 3 and 4 respectively secured thereto by tongues 5. Electrodes I and 2 are lseparated by separators or spacers' and 1. In use the assemblage of electrodes `l and 2 and 'spacers 6 and 1 may be rolled together into a rolled unit 8 as illustrated.

The electrodes,- as shown in Fig. 2, are formed of batts of textile `fibers 9 having vfibers ID of thermo-bonding material such as thermo-plastic or'thermo-setting material intermingled therewith. This figure also illustrates the velectrolytically active metallic particles Il deposited on and embedded within the mass of `fibers and coalesced therewith. It will be noted that 'said inetallic particles Il 'are bonded together at spaced points on their surfaces and to the Afibers 9 and I of the batt.

Figure 3 illustrates an electrodeV of `modified form differing from that shown in Fig. `2 inthat all of the fibers 9 `are of textile material. This electrode differs from that of Fig. `2 also in that particles I2 of thermobonding material "are intermingled 'with the fibers 9 and "serve to bond said'fibers together. Particles of metal Il are associated with the batt in the same manner as in Fig. `2.

JAstiil -further modified form of the electrode is 'shown |'in Fig. "4. In this instance, the batt is .formed of fibers 9 of textile material and fibers 'V0 'of thermo-bonding material. Intermingled with the fibers 9 and l0 are particles l2 of thermobonding material bonding the bers together. Particles of metal Il are associated with the batt in the same manner as in Fig. 2.

Electrodes made yaccording to my invention are porous throughout and may have one or more layers of spray deposited material applied thereto continuously by passing the calendered batts properly spaced before molten metal atomising equipment. They have great longitudinal strength and are inexpensive due tothe fact that weaving and twisting is unnecessary. It is possible to make `these calendered batts by using only natural Vtextile fibers with thermobonding particles distributed at spaced vintervals therev@prior to spraying with molten metal particles.

Unbleached cotton carded and dry laid into a 'battl having 4thermo-bonding material intervriii'ngled"therein is a suitable material and preferable 'to bleached cotton because it does not necessitate the removal of contaminating bleaching reagrit'si'therfrom prior to use in making my invention. Calendering can be done in two or more stages, if preferred with the deposition of molten metal particles between stages if prefered, accordingto invention, and the deposited molten metalparticles maybe usedsolely as bonding particles if preferred.

In addition to making batts as described herein of a `calendered thickness up to .004 'of an inch, it has been found that in some instances, it 'is preferable to "make the :batts of "textile bers bonded by thermoplastic material accord'- ing to either of the several `procedures hereinbefore described, but differing therefrom in that the wandered thickness vdf the 'bja-tt may 'range up to about .006 to .U08 of van inch. Such batts are particularly useful when it is"desired'totorm electrodes 'having porous 'coating layers of electrolytically active metallic particles deposited on both sides of the batt and 'embedded Iwithin 'the mass of the batt to su'ch'an extent thatv thecoating applied on one side `ofthe batt is electrically oonductiv'ely connected with the coating 'applied on the other side of the batt through the embedded particles.4

Electrodes made 'according to my 'invention are so ilexible that Whereas lordinary 'spraydeposited layers will crack 'on being folded at 411'30", or at least become appreciabl'y less conductive thereupon, electrodes made accordingto myfin'- ventioncan be` folded upon themselves fa'tapproximately 1'80"` without adversely aiecting'the .electricalconductivity thereof'appreciably. This makes it possible andpra'cticable to 'slit 'and/or cut 'andjfold along thel edge a'termirial 'co'nnetion of thesame material of wnich'thee'ctrod is composed. I

The thickness of the vbatt 'may b vgreaterthan lthe thickness specified according to my invention for making Velectrodes Aspray 'depositedfon and from both faces 'of the batt stripmateriaI, the limitation 'on thickness and porosity of the batt being that these characteristics `b`e such that the spray deposited particles penetrate into the body of the lstrip and substantially ,all lthe way throughiandthat these particles be bonded to eachother in electrical conductive relationship and cohere to 'each other to forni a unitary conductive body.

I lrind that I can get an increase `in 'capacity by making electrodes according to my linvelition of at least 10% increase vper unit of area over that of prior `commercial practice and I iind that for a given thickness of electrode and for a given cross section area thereof 1ongitudi-- nally I secure an increase in tensile strength -of at least 20% over any Vfibrous Wet laid materials.

I claim: n

1. An electrode for an electrolytic device comprising a calendered band of textile fibers disposed primarilylongitudinally thereof, a plurality of elements of thermo-bonding material intermingledwith Vsaid textile iibers and bonding said textile bels and VfOInl'Ilg 'a unitary plf''us mass, and electrolytically active metallic particles deposited on and embedded within said mass and coalesced therewith, said metallic particles being bonded together at spaced points on their surface and bonded to and interlocked with the fibers of said band to'form a conductive porous flexible electrode structure permeable to electrolyte.

2. An electrode for an electrolytic device comprising a calendered band of textile fibers disposed primarily longitudinally thereof, thermobonding plastic fibers intermingled with said textile fibers and bonding said textile fibers and forming a unitary porous mass, and electrolytically active metallic particles deposited on and embedded within said mass and coalesced therewith, said metallic particles being bonded together at spaced points on their surface and bonded to and interlocked with the fibers of said band to form a conductive porous flexible electrode structure permeable to electrolyte.

3. An electrode for an electrolytic device comprising a calendered band of unbleached cotton bers disposed primarily longitudinally thereof, a plurality of elements of thermo-bonding material intermingled with said textile fibers and bonding said textile fibers and forming a unitary porous mass, andlelectrolytically active metallic particles deposited on and embedded Within said mass and coalesced therewith, said metallic particles being bonded together at spaced points on their surface and bonded to and interlocked with the fibers of said band to form a conductive porous flexible electrode structure permeable to electrolyte.

An electrode for an electrolytic device comprismg a band of textile fibers disposed primarily longitudinally thereof, a plurality of synthetic plastic fibers mingled substantially throughout said band, plastic particles heterogeneously intermingled with said band, said plastic fibers and particles bonding said textile and forming a unitary porous mass, and electrolytically active metallic particles deposited on and embedded within. said mass and coalesced therewith, said metallic particles being bonded together at spaced points on their surface and bonded to and interlocked with the fibers of said band to form a conductive porous flexible electrode structure permeable to electrolyte.

An electrode for an electrolytic device comprising a calendered band of textile fibers disposed primarily longitudinally thereof, a plurality of elements of thermo-bonding material intermingled with said textile fibers and bonding said textile fibers and forming a unitary porous mass, and electrolytically active metallic particles deposited on and embedded within said mass and coalesced therewith, said metallic 1321110165 being bonded together at spaced points on their surface and bonded to and interlocked with the fibers of said band to form a conductive porous flexible electrode structure permeable to electrolyte, the content of thermo-bonding materlal ranging from 1 to 40%.

6. An electrode-forming tape for an electrolytic device comprising an elongated band of textile fibers with the fibers disposed pre nderan longitudinally of the band, and elerolyticali; active metallic particles deposited on and enibedded within said mass and coalesced therewith, said metallic particles being bonded together at spaced points on their surface and bonded to and interlocked with the fibers of said band to form a conductive porous flexible electrode structure permeable to electrolyte.

7. An electrode for an electrolytic device comprising a calendered band of textile fibers disposed primarily longitudinally thereof, a plurality of elements of thermo-bonding material 1ntermingled withsaid textile fibers and bonding said textile bers and forming a unitary porous mass and electrolytically active metallic particles deposited on both sides of the band and embedded within the mass of said band and coalesced therewith, said metallic particles on each side of the band being bonded together at spaced points on their surfaces and bonded to and interlocked with the bers of said band to form a conductive porous flexible electrode structure permeable to electrolyte, and some of the metallic particles of the layer on one side of the band penetrating into the band and electrically conductively connecting the layer on one side of the band with the layer on the other side of the band.

8. An electrode for an electrolytic device comprising a calendered band of textile fibers disposed primarily longitudinally thereof, and electrolytically active metallic particles deposited on both sides of the band and embedded within the mass of said band and coalesced therewith, said metallic particles on each side of the band being bonded together at spaced points on their surfaces and bonded to and interlocked with the fibers of said band to form a conductive porous flexible electrode structure permeable to electrolyte.

9. An electrode for an electrolytic device comprising a calendered band of textile fibers disposed primarily longitudinally thereof, thermobonding plastic fibers intermingled with said textile fibers and bonding said textile fibers and forming a unitary porous mass having a predetermined calendered thickness and electrolytically activemetallic particles deposited on both sides of the band and embedded within the mass of said band and coalesced therewith, said metallic particles on each side of the band being bonded together at spaced points on their surfaces and bonded to and interlocked with the fibers of said band to form a conductive porous exible electrode structure permeable to electrolyte, and some of the metallic particles of the layer on one side of the band penetrating into the band and electrically conductively connecting the layer on one side of the 'band with the layer on the other side of the band.

JOSEPH B. BRENNAN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,104,018 Brennan v- Jan. 4, 1938 2,336,267 Lester Dec. '1, 1943 2,460,674 Bihaly Feb. 1, 1949 2,476,283 Castellan July 19, 1949 OTHER REFERENCES Kline et al., Airplane Dopes Industrial and ilglneering Chemistry, vol. 30, No. 5, pages 542- 

1. AN ELECTRODE FOR AN ELECTROLYTIC DEVICE COMPRISING A CALENDERED BAND OF TEXTILE FIBERS DISPOSED PRIMARILY LONGITUDINALLY THEROF, A PLURALITY OF ELEMENTS OF THERMO-BONDING MATERIAL INTERMINGLED WITH SAID TEXTILE FIBERS AND BONDING SAID TEXTILE FIBERS AND FORMING A UNITARY POROUS MASS, AND ELECTROLLYTICALY ACTIVE METALLIC PARTICLES DEPOSITED ON AND EMBEDDED WITHIN SAID MASS AND COALESCED THEREWITH, SAID METALLIC PARTICLES BEING BONDED TOGETHER AT SPACD POINTS ON THEIR SURFACE AND BONDED TO AND INTERLOCK WITH THE FIBERS OF SAID BAND TO FORM A CONDUC TIVE POROUS FLEXIBLE ELECTRODE STRUCTURE PERMEABLE TO ELECTROLYTE. 